Aromatic compounds have a multitude of uses, both as end products and as reactants for downstream processes. Methods of preparing aromatic compounds from a hydrocarbon feed are generally known in the art and include upgrading the hydrocarbon feed followed by reforming and aromatics separation. Typical upgrading techniques include hydrotreating to remove contaminants such as sulfur, nitrogen, and oxygen. After upgrading, the hydrocarbon feed is reformed in the presence of a catalyst to convert paraffins and naphthenes to a reformate that includes aromatic compounds such as xylenes, benzene, and toluene. A series of separation techniques are employed to separate the various aromatic compounds from the reformate, and numerous product streams having varying degrees of purity may be isolated for each aromatic compound in the reformate.
Hydrocarbon streams that are provided for upgrading generally include compounds that have from 6 to 10 carbon atoms, and the hydrocarbon streams may be derived from crude oil. To obtain the hydrocarbon streams including compounds that have from 6 to 10 carbon atoms, the crude oils is generally separated in a crude distillation unit, with various streams produced by the crude distillation unit including, but not limited to, various streams that primarily include compounds that have less than 6 carbon atoms and a crude bottoms stream including compounds that have greater than 10 carbon atoms. The crude bottoms stream can be cracked, such as in a fluid catalytic cracking (FCC) unit, to convert relatively high boiling point hydrocarbons (e.g., compounds that have higher numbers of carbon atoms) to lower boiling point hydrocarbons (e.g., compounds that have lower numbers of carbon atoms), resulting in a full boiling range (FBR) naphtha stream. The FBR naphtha stream generally contains paraffins, naphthenes, aromatics, unsaturated compounds, such as open-chain and cyclic olefins, dienes and cyclic hydrocarbons with olefinic side chains, with the compounds having a range of numbers of hydrocarbons. The FBR naphtha stream may be separated, such as in a naphtha splitter, to produce a C6 to C10 cracked stream that includes compounds having from 6 to 10 carbon atoms. The C6 to C10 cracked stream may be combined with the hydrocarbon stream that includes compounds that have from 6 to 10 carbon atoms from the crude distillation unit. However, the C6 to C10 cracked stream generally has a high amount of aromatic compounds that, while generally unaffected by reforming, result in unnecessarily increased loads on reforming units that are employed for reforming the hydrocarbon stream from the crude distillation unit.
While solutions have been proposed to avoid combining the C6 to C10 cracked stream with the hydrocarbon stream that includes compounds that have from 6 to 10 carbon atoms from the crude distillation unit, hydrotreating of the C6 to C10 cracked stream is still generally necessary to remove the contaminants from the C6 to C10 cracked stream. However, if the C6 to C10 cracked stream is kept separate from the hydrocarbon stream from the crude distillation unit, a separate hydrotreating unit becomes necessary to remove the contaminants from the C6 to C10 cracked stream, thereby increasing unit costs.
Accordingly, it is desirable to provide novel processes and apparatuses for preparing aromatic compounds that enable contaminants to be removed from a feed stream that includes an aromatic component, a non-aromatic component, and the contaminant. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.